Makes the golem go in specified direction. This is a really stupid function when you get down and look at it. Keep it here for the time being - makes life easier if we ever decide to do more interesting thing with controlled golems.

Given that 'pet' is a friendly object, this function returns a monster the pet should attack, NULL if nothing appropriate is found. it basically looks for nasty things around the owner of the pet to attack. This is now tilemap aware.